Gelfond and Lifschitz introduce a declarative language A for describin
g effects of actions and describe translations of theories in this lan
guage into extended logic programs. In this paper we extend the langua
ge A and its translation to allow reasoning about the effects of concu
rrent actions. The logic programming formalization of situation calcul
us with concurrent actions presented in the paper is of independent in
terest and may serve as a test bed for the investigation of various tr
ansformations and logic programming inference mechanisms. (C) Elsevier
Science Inc., 1997.